Means for securing the rotor on to its shaft in a pump for fluids



Oct. l, 1963 l R. GABBIONETA MEANS FOR SECURING THE RoToR oN To I'rs SHAFT IN A PUMP FOR FLUIDS Filed Jan. 50,v 1962 INVENTOR ROBERTO GHBBIONETH ATTORNEY United States Patent 3,105,445 MEANS FR SECURDIG TEE RTR N T@ HS SHAFT EQ A PUE/il FR FLUIDS Roberto Gabhioneta, Via L. Gasparotto 4, Milan, italy Filed Jan. 30, 1962, Ser. No. 1693354 Ciaims priority, application italy Feb. 17, 1961 7 Claims. (Cl. 19E-1M) The present invention relates to a pump for fluids and, n particular, a pump of the type which comprises a rotor provided with a protective coating of plastic material.

As is known, in pumps with rotors provided with protective coatings, eg. with their rotors coated with ebonite, the coating of said rotor and of other parts of the pump serves to preserve those metal parts, such as the core of the rotor itself, which would otherwise very soon be irremediably damaged by the fluid being pumped, containing corrosive substances.

-ln pumps of this nature, a problem of no little dihiculty lies in how best to secure the rotor to the supporting and driving shaft thereof, as it is not only necessary to secure these parts rmly together, but it is also necessary to provide a seal at the free edge of the ebonite coating of the rotor in order to prevent iniiltrations of said corrosive liquid.

There are known systems for securing the rotor to the shaft, but these systems present some considerable drawbacks.

According to one of said systems, the rotor is screwed on to the shaft of the pump, but this system, although it is relatively simple to apply, notoriously involves certain obstacles to good power transmission.

In a pump of this kind, if, for any reasons, the shaft of the pump were to rotate in the opposite direction to that of normal operation, the rotor would become unscrewed from the shaft.

According to another fastening system of known type, the rotor is secured to the shaft by means of a suitable tension rod housed inside the bore of the shaft.

r[his system employing such tension rod does provide a certain reliability of fastening of the rotor, but it presents several drawbacks such as, for example, the fact that there is unwanted play between the tension rod and the surface of the axial bore wherein the tension rod is situated, and the fact that the stripping of the rotor requires fairly complicated operations.

It is, therefore, one object of the present invention, to provide means for securing a rotor to a shaft, such as to obtain a reliable fastening without the ydrawback of the kind hereinabove mentioned.

It is another object of the present invention, to provide means for securing a rotor to a shaft which will also enable the rotor to be easily mounted and taken down.

It is yet another object of the present invention to provide means for securing a rotor to a shaft, which comprises a hollow cylindrical hub rendered integral at one end thereof with the rotor, a tubular protecting member pushed over the hub, and a gasket between the end of the latter member facing the rotor and that part of the plastic coating surface facing said end, there being provided a nut or similar means which is screwed on to the other end of the hub in such manner as to squeeze the member and the gasket against the rotor, and a second nut or similar means adapted to be screwed on to the first nut aforesaid which, for this purpose, is formed with an outer thread matching the inner thread of the aforesaid second nut, the latter being further provided with a part projecting radially towards the axis and adapted to be stopped in the course of its axial movement towards the rotor against a knockup or shoulder HCC of the pump shaft. The complex comprising the rotor, the hollow cylindrical hub, the tubular member and the nut screwed thereon, is fixed to the shaft by placing the hub over the shaft itself and screwing the second nut on to the rst nut, with the result that the abutment of the second nut against the shoulder of the shaft causes, as the second nut continues to be rotated, the penetration of the first nut into the second nut until such time as the hub, which, together with the rotor, follows the first nut in the axial movement, comes up against a second knockup on the shaft of the pump, there being provided means for rendering the hub, the tubular member and the second nut itself integral with the shaft in its rotation, and it being further provided that the two nuts are internally threaded in the same direction, i.e. in such a manner that the direction of their screwing home rotation is contrary to the direction of rotation of the shaft during the normal operation of the pump, the thread of the second nut having a greater pitch than the internal thread of the iirst nut which is screwed on to the hub.

With these and other objects in View, which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawing, in which the only FIGURE is an axial section of a pump including a device for securing the rotor to the shaft in accordance with the present invention.

Referring now to the drawing, the pump comprises a rotor which includes a metal core ll provided with an ebonite coating l.

A cylindricalinternally bored hub 2 provided with a longitudinal spline 3 is rigidly secured to the rotor A and, to this end, in the shown embodiment, the rotor A is screwed on to the end 2 of the hub 2 and, thereafter, held in position by means of dowels d.

The core 'il of the rotor A vand the hub 2 are made yof material which is not resistant to the corrosive action of the liquid to be fed through the pump. The liquid may, for example, consist of a s-aline solution containing dissolved `chlorine gas or HCl. Therefore, in order to protect the hub 2 of the rotor A, a sleeve :consisting of la tubular member 5 of anti-acid material is provided. As may be seen in the drawing, the sleeve 5 extends over the whole length of that portion of the hub 2 which is disposed between the end threads 2 `and 2" of the hub 2.

Between `the end of the sleeve 5 facing the rotor A, rand in particular the left hand end, as seen on the drawing and the portion of the ebonite covering wall fr facing this end of the sleeve 5, there is provided a gasket 6 which is resistant to acid. The gasket 6 is squeezedv by :the sleeve 5 against the portion of the surface of the coating l', as Iwill be apparent hereinafter, and, thereby, protects the metal parts of the rotor A and prevents infiltration-s of liquid.

In order to connect the hub Zand the sleeve 5 to joint rotation, a key 19 engaging in the two last mentioned elements is provided.

There is also arranged a nut 7 which is screwed to the threaded end 2" olf the lhub 2, so .as to urge the sleeve 5 against the gasket 6, in `order to provide a good seal.

In order to connect lthe hub 2 with the shaft 3 of the rotor A for joint rotation, `a key 9 is provided on the shaft 3 which is received in the `slot 3 of the hub 2.

The nut 7 is also equipped with an outs-ide thread 7' which matches the inner thready lh of a second nut it, `adapted to fasten the members of ythe complex consisting of the rotor A, the hub 2, the sleeve 5 `and the nut 7 to the shaft 8.

The shaft S is :formed Iwith an `annular rib il and an rannular shoulder 12, ythe nut l0 abutting the annular 3 rib 11 and the hub 2 abutting the annular shoulder 13 in the process of securing these parts together as stated hereinbefore. The nut l() has aradial passage 212i receiving a stop dowel 13. Y

There are also provided a packing ring 14 and a cover ring 15, each of the rings 414 Iand -15 being formed of two half rings 4and fastened to fixed parts of the pump. By removing one half ring of the cover 15', for instance the lower half, the dowel 13 is conveniently accessible. The direction of the inner thread is the same for the Iltwo nuts 7 Iand 10; for example, if the pump should rotate in a clockwise `direction looking from the side opposite to the driving end, then the threads of the nuts 7 and 19 will be right-handed.

Moreover, for reasons which will more clearly appear hereinafter, ythe pitch of the thread of the nut 1S is greater than the pit-ch of the yinner thread of the nut 7.

It is assumed, as an example only and without limiting the present invention, that the pitch of the inner thread `of the nut 10 and that of the inner thread of the nut 7 are, respectively, 2 mm. and 1.5 mm.

Y In vorder to mount the rotor on the shaft 8, the cover 17 of the pump is taken olf the fixed pump body 18 and the rotor A with its hub 2 and the sleeve 5' lare outside of the pump body 18.

The rotor A, as stated hereinbefore, comprises a core y1 which has an ebonite coating 1', and is connected with the hub 2; the gasket 6 and the sleeve 5 are now inserted over the hub 2 so that the hub 2 and the sleeve come into engagement by means of the key 19:

A second gasket is placed over the hub 2 yat the threaded end 2'. and the nut 7 is screwed on to the threaded end 2" of the hub 2.

When the nut 7 is tightened, :the sleeve 5 is urged thereby against the gasket 6, which is thereby firmly gripped between the sleeve 5 andthe rotor A.

The entire assembly is inserted into the pump body 1S and the hub 2 is moved over the shaft 8 in such manner as to provide an engagement with the'shaft 8 by means of the key 9 which is received in the spline or slot 3 of the shaft 8.

`lf the nut is turned, while the shaft 8 is held firm, it is screwed on to the nut 7.

More precisely, the nut 10 tends to move to the left, viewing the drawing, so that, when it abuts the rib 11, it stops its axial movement; if the nut 1G continues its turning, the nut 7 itself moves to the right, viewing the draw'- ing, and thus enters into the nut lil.

The axial movement of the nut 7 in this direction transfers this movement to the who-le assembly of the rotor A, namely the nut 7, the hub 2 and the sleeve 5.

The nut 1@ continues then the turning until such time as the right hand end, viewing the drawing, of the hub 2 abuts the annular shoulder 12 of the shaft S; the tightening of the nut 10 thus brings abou-t the tightening of the hub 2 against the annular shoulder 12 and, hence, a firm securing of the rotor A to the shaft S.

It should be noted that, since the direc-tions of turning of the nut 1t? on the nut 7 and of the nut 7` on the hub 2 are identical during the turning of the nut .111, there may be a greater tightening of the nut 7 and hence, of

The suction and delivery orices are indicated respec` tively by the letters A and M.

During the operation of the pump, the rotor A, the hub 2, the sleeve 5 and the nuts 7 and 11i rotate jointly with the shaft i5 for the reasons set forth above.

By the arrangement set forth above,Y even if, for any reason, the shaft 8 were caused to rotate in the opposite direction to that of normal operation, the respective members of the entire assembly would remain in a position connected with each other.

Tlhus, the shaft 8 and the 'hub 2 are connected to joint rotation by means of the key 9; the sleeve 5 and the hub 2 are connected -to joint rotation by means of the key 19; and lthe nut 1n is fastened to the shaft 8 by means of the set screw 13.

The nut 7 cannot 4likewise perform any movements relative to the shaft 8.

If the nut 10 tends to be loosened from the end 2 of tre hub 2, by rotating in the proper direction, the nut 7 must screw itself further into the nut l@ and furthermore it must move towards the right, viewing the drawing, together with the hub 2.

More precisely, since the inner thread of the nut 1? is `of greater pitch than the inner thread of the nut 7, when the latter performs 1an axial movement inside the nut 1i?, towards the rig-ht, viewing the drawing, there would be obtained an axial movement or" the nut 7 in relation to the hub 2, which movement will be proportionate to the pitch of the nut 7 and lalso an axial movement of the assembly consisting of the nut 7 and the hub 2, which will be proportionate to the difference in the pitches in relation to the shaft 8.

The movement of the assembly of the nut 7 and the hub 2 is impossible, because the hub 2 is in engagementV with the annular shoulder 12.

lt is now supposed, for example, that the pitches of the nuts 7 and 1i? are respectively 1.5 nim. and 2 mm.

1n order to make an yaxial movement, eg. of 2 mm. into the nut 1d, the nut 7 would have to rotate in relation to the hub 2 4and shift axially in relation thereto for a distance of 1.5 mm., to the right viewing the drawing; furthermore, for the remaining 0.5 mm. the assembly of the nut 7 and the hufb 2 would have to shift to the right, viewing the drawing, since, in this movement, the nut 7 and `the hub 2 are jointed for common rotation.

This movement of 0.5 mm. is impossible, as .already stated, because of the annular shoulder 12 against which the hub 2 abuts.

if the rotor is to be disassembled, such operation can be performed with simplicity and rapidity.

lf the pump is not in operation and the shaft 8 is held firm -by the coupling 22, when the set screw 13 has been extracted, it is only necessary to unscrew the nut 10 from the nut 7 using a suitable tool. Y

At first the nut 111 will move to the right, viewingrthe drawing, until it engages the shoulder 2?)` of the cover 15. Thereafter, if the nut 1t) continues its rotation, since it cannot shift axially on account of the shoulder 23, it is the nu-t 7 which will'move to the left, viewing the drawing, together with the 'entire assembly of the rotor A, the hub 2 and `the sleeve 5, which will thus be'removed from the pump, provided that the cover 17 has been removedY previously.

Besides the aforesaid function of keeping the hub 2, and hence the rotor A, in abutment against the annular shoulder 12 of the shaft S during operation, the nut 1li also serves as a means for extracting the rotor A, as set forth above.

The pump described hereinabove olers considerable advantages, such as the reliable securing of the rotor A and the sealing thereof, together with the facility of the operations of mounting and disassembling `the rotor A itself. A further advantage resides in the fact, that the nut 7 not only cannot be loosened for reasons set forth above, but it can also be tightened at will from the outside,

when the pump is not in operation, without removing any -other part of the pump, with the exception of the packing ring 14, which is formed of two halves.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by way of example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. A pump for iiuids, including a rotor provided with a protective coating of plastic material, comprising a pump shaft,

said rotor having said plastic coating and a hollow cylindrical hub secured at one end thereof to said rotor,

a tubular protective member encircling said hub,

a gasket Idisposed between the end of said tubular protective member facing said rotor and the part of the surface of said plastic coating facing said one end of said hub,

a rst nut having inner thread and outer thread screwed to the outer surface of the other end of said hub, thereby urging said tubular protective member and said gasket against said rotor,

a second nut having inner thread screwed to said outer thread of said iirst nut,

said pump shaft being set of at points axially spaced apart Ifrom each other and to form a first annular shoulder and a second annular shoulder,

said second nut having an annular radially inwardly extending ring abutting said iirst lannular shoulder of said pump shaft, in order to limit the axial movement of said second nut towards said rotor, whereby the assembly, consisting of said rotor, said hollow cylindrical hub, said tubular protective member and said first nut screwed on to the latter, is secured to said pump shaft by placing said hub on said pump and screwing said second nut on said first nut,

so that upon abutment of said second nut against said rst annular shoulder of said pump shaft during continued rotation of said second nut, said first nut penetrates into said second nut until said hub with said rotor, lfollowing the axial movement of said first nut, abuts against said second annular shoulder of said pump shaft,

means connecting said hub, said tubular protective member and said second nut lfor joint rotation with said shaft, the inner thread of said iirst nut being in the same direction as the inner thread of said second nut and the direction of said inner threads of said first nut and of said second nut being contrary to the direction of rotation of said pump shaft during normal operation of said pump, and

said inner thread of said second nut being of greater pitch than said inner thread of said rst nut.

2. The pump for uids, as set forth in claim 1, wherein said rst annular shoulder comprises an annular rib integral with said pump shaft. 3. The pump -for uids, as set forth in claim l, wherein Isaid second annular shoulder is a set-off face of said 5 pump, said set-off face being disposed perpendicularly to the axis of said pump, and the diameter of the latter being different yat the opposite sides of said set-Gif face. 4. The pump for fluids, as set forth iin claim l, which includes a packing means surrounding said tubular protective member and a packing ring secured to said pump body and surrounding said tubular protective body, and said packing ring comprises two hallves complementing each other. 5. The pump for iiuids, as se-t forth in claim l, wherein said means for connecting said hub and sadtubular protective member and said second nut for joint rotation comprises a rst key secured to said pump shaft and said hub having a longitudinal slot disposed on its inner surface and receiving said iirst key, and a second key secured to said hub, and said tubular protective member having a longitudinal slot disposed on its inner surface and receiving said second key, said second nut having a radial bore, and a set screw received in said bore and engaging with its inner end said pump shaft, in order to secure said `second nut to said pump shaft. 6. The pump for fluids, as set forth in claim 5, which includes a pump body spaced apart yfrom and surrounding said pump shaft, a cover ring surrounding said second nut and fastened to said pump body, said cover ring including an abutment face disposed perpendicularly to the axis of said pump shaft, and said abutment limiting an axial movement of said second nut in the direction away from said first abutment .face of said pump shaft. 7. 'Ihe pump for uids, as set forth in claim 6, wherein said cover ring comprises two half rings complementing each other and divided by a plane passing ,through the axis of said cover ring.

References Cited in the le of this patent UNITED STATES PATENTS 

1. A PUMP FOR FLUIDS, INCLUDING A ROTOR PROVIDED WITH A PROTECTIVE COATING OF PLASTIC MATERIAL, COMPRISING A PUMP SHAFT, SAID ROTOR HAVING SAID PLASTIC COATING AND A HOLLOW CYLINDRICAL HUB SECURED AT ONE END THEREOF TO SAID ROTOR, A TUBULAR PROTECTIVE MEMBER ENCIRCLING SAID HUB, A GASKET DISPOSED BETWEEN THE END OF SAID TUBULAR PROTECTIVE MEMBER FACING SAID ROTOR AND THE PART OF THE SURFACE OF SAID PLASTIC COATING FACING SAID ONE END OF SAID HUB, A FIRST NUT HAVING INNER THREAD AND OUTER THREAD SCREWED TO THE OUTER SURFACE OF THE OTHER END OF SAID HUB, THEREBY URGING SAID TUBULAR PROTECTIVE MEMBER AND SAID GASKET AGAINST SAID ROTOR, A SECOND NUT HAVING INNER THREAD SCREWED TO SAID OUTER THREAD OF SAID FIRST NUT, SAID PUMP SHAFT BEING SET OFF AT POINTS AXIALLY SPACED APART FROM EACH OTHER AND TO FORM A FIRST ANNULAR SHOULDER AND A SECOND ANNULAR SHOULDER, SAID SECOND NUT HAVING AN ANNULAR RADIALLY INWARDLY EXTENDING RING ABUTTING SAID FIRST ANNULAR SHOULDER OF SAID PUMP SHAFT, IN ORDER TO LIMIT THE AXIAL MOVEMENT OF SAID SECOND NUT TOWARDS SAID ROTOR, WHEREBY THE ASSEMBLY, CONSISTING OF SAID ROTOR, SAID HOLLOW CYLINDRICAL HUB, SAID TUBULAR PROTECTIVE MEMBER AND SAID FIRST NUT SCREWED ON TO THE LATTER, IS SECURED 